M104 is numerically the first object of the catalog which was not included in Messier's originally published catalog. However, Charles Messier added it by hand in his personal copy on 11th May 1781 as a "very faint nebula." It was Camille Flammarion who found that its position coincided with Herschel's H I.43, which is the Sombrero galaxy, and added it to the official Messier list. This object is also mentioned by Pierre Mechain as his discovery in his letter of May 1783. William Herschel found this object independently on May 9, 1784.

This brilliant galaxy was named the Sombrero Galaxy because of its appearance. According to de Vaucouleurs, we view it from just 6 degrees south of its equatorial plane, which is outlined by a rather thick dark rim of obscuring dust. This dust lane was probably the first discovered, by William Herschel in his great reflector.

This galaxy is of type Sa-Sb, with both a big bright core, and as one can see in shorter exposures, also well-defined spiral arms. It also has an unusually pronounced bulge with an extended and richly populated globular cluster system - several hundred can be counted in long exposures from big telescopes.

Recent very deep photographs from the Anglo-Australian Observatory show that this galaxy has a very extended faint halo.

This galaxy was the first one with a large redshift found, by Vesto M. Slipher at Lowell Observatory in 1912. Its redshift corresponds to a recession velocity of about 1,000 km/sec (it is caused by the Hubble effect, i.e. the cosmic expansion). This was too fast for the Sombrero to be an object in our Milky Way galaxy. Slipher also detected the galaxy's (then the nebula's) rotation.

This is NOT a flying saucer! Messier 104 is a spiral galaxy (type Sa-Sb) seen in a nearly edge-on configuration. The large and bright central bulge of the galaxy is encircled by a flattened spiral disk, which appears as a ring of dust and stars from our viewing angle.

Visible: DSS (left) and VLT ANTU + FORS1 (right)

The visible-light images from DSS (above, left) and VLT (above, right) clearly reveal the obscuring dust in the foreground edge of the galaxy disk. If you look closely at the DSS image, you should even be able to tell that the dust disk is warped. Such warps are often the result of a close gravitational encounter with another nearby galaxy.

Visible: TIE (left) and Near-Infrared: 2MASS (right)

The exposure time for the TIE image (above, left) was of relatively short duration. Hence the brightness of the central bulge is reduced from more sensitive visible-light pictures displayed above. The dust lane within the disk is, however, still prominent.

Now look at the near-infrared image and compare with the companion TIE optical photo. See any difference? You will find that the obscuring dust is much less evident in the 2MASS picture. This is good illustration of how near-infrared light can pierce through obscuring dust and why astronomers rely on near-IR measurements to study star formation, which typically occurs in dusty interstellar environments. For an even more remarkable contrast of images, check out the optical and near-IR views of the heavily obscured center (at optical wavelengths, anyway!) of our Milky Way Galaxy.

Mid-Infrared: IRAS (left) and Far-Infrared: IRAS (right)

The mid- and far-infrared images were taken with the space-borne IRAS satellite in 1983. The mid-IR image (above, left) barely reveals the emission from the central galaxy (green). The surrounding weak signals (blue) are noise akin to the snow you might see on a television set with poor reception.

The far-infrared photo (above, right) clearly shows emission from Messier 104. Very little detail is evident, however, since the IRAS detectors were of relatively poor spatial resolution. Future IR telescopes, such as SIRTF, will have far better resolution and will be capable of producing much finer images of galaxies like M104.

Radio: NVSS (left) and X-Ray: ROSAT (right)

The images immediately above appear similar, but were taken by telescopes at opposite ends of the electromagnetic spectrum! The radio image (left) shows a central peak of bright emission (in red), but very little else. If the radio emission followed the visible-light distribution shown in the first images of this gallery (top of the page), we would expect to see the radio emission spread into a flattened ellipse. Since the radio emission is essentially point-like and is centrally located, we conclude that the source of the naturally-produced radio waves is the central bulge of M104, and not the extended disk.

Finally, the x-ray picture (above, right) also shows a central source of emission. By coincidence, the false colors used in the x-ray image closely resemble those used in the radio image. Unlike the radio map, however, two additional sources of x-rays appear in the field of view. According to the NASA Extragalactic Database (NED), these secondary x-ray sources have been cataloged as x-ray sources. Their exact nature cannot be determined until astronomers measure their distances using spectroscopy (the use of spectrum analysis).

On the internet we found some exploration, which were made by sciences. Here is one of them:

Observation Poster: Jim Aderson <madmoon@bellsouth.net>

Observer: Jim Aderson

Your skills: Intermediate (some years)

Date/time of observation: 05012000/22:00CST

Location of site: Prude Ranch, Ft. Davis, TX (Lat 30.1N, Elev ?)

Site classification: Rural

Sky darkness: 9/10 <1-10 Scale (10 best)>

Seeing: 7/10 <1-10 Seeing Scale (10 best)>

Moon presence: None - moon not in sky

Instrument: 30CM, F:10, SCT, LX200

Magnification: 203x

Filter(s): None

Object(s): NGC4594 (M104)

Category: External galaxy.

Class: Sa

Constellation: Vir

Data: mag 8.0v size 8.9' x 4.1'

Position: RA 12:40.0 DEC -11:38

Description:

203x - NGC4594 (M104) is a spiral galaxy seen near edge on. It is tilted toward the viewer about 5 degrees so you are seeing the top of the disk and a littleof the spiral arms on the far side. The core is round and very bright, but without a stellar nucleus, rather a small oval area that is a little brighter than the core it's self. The core fades toward it's boundry with the a globe of haze, the halo, aproximately 1/3 the size of the whole galaxy is quite evident even with direct vision. The spiral arms are easy bright with the obscuring

dust lane, like a tire around the rim of a solid looking wheel. The dust lane is narrow and dense, appearing to completely obscure the light from beyond. The top edge seems to be pretty sharp, while the bottom edge seems a little soft and with a little motteling. The ends of the dust lane seem to wrap around

and extend back toward thw core, but fade away behind the hazy halo. Above the galaxy is a stream of stars with one much brighter than the remainder. There is a relatively bright stsr just below the halo and another near above, superimposed on the haze.

We think what everyone can trust or cannot trust that information which did the Jim Aderson wrote. Because he is an intermediate and so he is not professional and he hasn't much experience, but it's isn't a very hard object because it's far away.

The future and the pastGo to the begining Sombrero Galaxy (M104) in the Virgo Cluster of Galaxies - a beautiful object.
It takes Light about 65 million years to reach Earth from this cluster.
65 million years ago on Earth were Ice period and all dinosaurs died.
So if we are talking about the future of Sombrero galaxy,
we are talking about it's past.
Comparison

A set of photographies of several galaxies will be given to the participants.

There are different types from ground - planned to edge on. By measuring them using common

geometric tools, the participants will recognize the axes of these galaxies and then will

calculate the galaxies compression degree e.

M 104 M 32

Exercise:

To determine the type of the galaxies reflected in the picture according to Habl`s classification

and the compression degree e of elliptical galaxies.

e = 10×(a - b)/a

where e - the compression degree

a - lenght of the longest axes of galaxy

b - lenght of the shortest axes of galaxy

Special Thanks
Project was done by Jury Leonenko and Vitally Gailis.
Special thanks to Charles Messier for his discoveries,
thanks to our Physics and Astronomy teacher Inese Dudareva for her help in our project,
big thanks to teacher Erinsh and Yanis Pildavs.
Thanks to our mums and dads Irena Leonenko, Sergio Tokalchik
and Jelena Gaile, Aivars Gailis for their support.
Thank you for attention.